Isolation by HPLC of the positional isomers of heterogeneous doubly branched cyclomaltohexaose having one α-d-galactosyl and one α-d-glucosyl side chain and determination of their structures by enzymatic degradation

Each of the six and five positional isomers of 2n- and 6n-O-α-d-galactopyranosyl-61-O-α-d-glucopyranosyl-cyclomaltohexaose (α-cyclodextrin, αCD; 2n: n = 1–6, 6n: n = 2–6), which were produced from 6-O-α-d-glucopyranosyl-αCD and melibiose by transgalactosylation with coffee bean α-galactosidase, were isolated by high-performance liquid chromatography (HPLC) on a reversed-phase column and a graphitized carbon column. The structures of those isomers were elucidated by analyses of enzymatic degradation products with cyclomaltodextrin glucanotransferase and glucoamylase.